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West Pacific/2015/11W/Archive/16
Public advisory TYPHOON NANGKA PUBLIC ADVISORY NUMBER 16 WIKI-HURRICANES FORECASTING CENTER 12:00 PM JST TUE JUL 07 2015 ...TYPHOON NANGKA NOW AN UPPER-END CATEGORY 3 CYCLONE... SUMMARY OF 12:00 PM JST...03:00 UTC...INFORMATION ------------------------------------------------------------------- LOCATION...13.5N 155.0E CENTER POSITION CONFIDENCE: HIGH ABOUT 635 MI...1,020 KM ESE OF SAIPAN, MARIANA ISLANDS MAXIMUM SUSTAINED WINDS...110 KT...125 MPH...205 KM/H MINIMUM BAROMETRIC PRESSURE...936 MB...27.64 INCHES PRESENT MOVEMENT...WNW AT 11 KT...13 MPH...21 KM/H DISCUSSION AND 48-HOUR OUTLOOK --------------------------------------------- At 6:00 am JST, the center of Typhoon Nangka was situated near 13.5N 155.0E, or about 635 miles (1,020 km) east-southeast of Saipan, Mariana Islands. Maximum sustained winds were 110 knots (125 mph, 205 km/h), with higher gusts. The minimum barometric pressure was 936 millibars (hPa; 27.64 inHg), and the cyclone was tracking west-northwest at 11 knots (13 mph, 21 km/h). Additional intensification, perhaps rapid at times, is expected over the next 48 hours as Nangka remains steady in trajectory. NEXT ADVISORY ------------------- Next complete advisory at 6:00 pm JST. $$ Forecaster TAWX14 Discussion TYPHOON NANGKA DISCUSSION NUMBER 16 WIKI-HURRICANES FORECASTING CENTER 12:00 PM JST TUE JUL 07 2015 Nangka has become substantially better organized since the previous advisory. Infrared satellite animations indicate that the convection within the eyewall of the cyclone has become much more uniform. The eye, which was misshapen earlier, is now circular and warming. A microwave pass shortly after 21z indicated a bonafide and closed eyewall. Recent satellite intensity estimates were T5.5/102kt from SAB, T5.5/102kt from JTWC, and T6.3/122.2kt from UW-CIMSS ADT. Given that information, the initial intensity has been sharply raised to 110kt, making Nangka an upper-end Category 3 cyclone. Maps from UW-CIMSS indicate that Nangka is approaching a region of increased vertical wind shear on the order of 15 to 25 knots courtesy of an upper-level trough to the cyclone's north and west. However, the flow around the trough becomes more divergent as it approaches Nangka, suggesting that conditions may not be quite as unfavorable as they otherwise would be. Given this information, combined with recent trends as far as the intensification of the storm is concerned, the intensity forecast has been raised in the short term. As the cyclone passes the Mariana Islands in approximately 72 hours, environmental conditions are expected to be most favorable, and Nangka is now expected to attain Category 5 intensity. Thereafter, the approach of an upper-level trough from the north may impart stronger shear and prompt at least temporary weakening. Nangka is currently tracking swiftly west-northwest under the influence of a potent mid-level ridge across the northern West Pacific. This steering regime is expected to remain in place for the next 72 hours or so. Thereafter, the aforementioned upper-level trough is expected to erode the western periphery of the ridge and cause Nangka to turn more poleward at a slower rate. Both the GFS and ECMWF remain in generally good agreement throughout the forecast period, and the updated track forecast is largely unchanged from the previous one. On its current path, Nangka is expected to pose a substantial threat to the northern and central Mariana Islands, and residents there should prepare for potentially life-threatening conditions. INIT 07/0300Z 13.5N 155.0E 110 KT 125 MPH 12H 07/1200Z 14.1N 153.4E 120 KT 140 MPH 24H 08/0000Z 15.0N 151.2E 125 KT 145 MPH 36H 08/1200Z 16.1N 149.4E 130 KT 150 MPH 48H 09/0000Z 17.5N 147.6E 135 KT 155 MPH...NEAR NORTHERN MARIANA ISLANDS 72H 10/0000Z 19.4N 144.4E 140 KT 160 MPH 96H 11/0000Z 20.7N 142.7E 130 KT 150 MPH 120H 12/0000Z 22.6N 142.0E 120 KT 140 MPH $$ Forecaster TAWX14